Show / hide rows of a table

My client has a lot of tabular data to add to their website. Every three rows in four need to be hidden when the page loads and revealed on a click. I know this is fairly straightforward using javascript but I’m not sure how to tell the script exactly what elements to hide – I don’t want my client to have to access the HTML and add css to the relevant rows.

I was hoping to nest the data that needs to be hidden in tables within the main table so that I can use javascript to hide all occurrences of ‘table table’. But so far I can’t see how to nest a table within a table, not with any of the plugins available or just basic tables in a post.